Typically, a general internal combustion engine vehicle uses fossil fuel such as gasoline, diesel, or the like and the fuel contributes to environmental pollution due to exhaust gas, global warming due to carbon dioxide, a cause of a respiratory disease due to an ozone generation. Further, a limited amount of the fossil fuel exists on the earth and may be exhausted. In order to solve the above-mentioned problems, eco-friendly vehicles such as an electric vehicle (EV) driven by driving an electric motor, a hybrid electric vehicle (HEV) driven by an engine and the electric motor, a fuel cell electric vehicle (FCEV) driven by driving the electric motor by power generated from a fuel cell, and the like have been developed.
The above-mentioned eco-friendly vehicles, which are low-emission vehicles capable of minimizing an environmental problem and a problem of resource exhaustion, or zero emission vehicles capable of solving the above-mentioned problems, include an electric motor, a high voltage battery, a low voltage battery, a low voltage direct current (DC)-DC converter. When the low voltage DC-DC converter simultaneously performs a filtering during an initial driving as illustrated in FIG. 1, a de-rating response reaction is delayed and an over-current A occurs. When the low voltage DC-DC converter is shutdown due to the over-current, electronic loads are supplied with power through an auxiliary battery. However, when the auxiliary battery is fully discharged, the vehicle may be shutdown, thereby causing an accident.